1. Field of the Invention
This invention relates generally to a coupling arrangement for attaching equipment to a vehicle. More particularly, this invention relates to a plural coupler for attaching equipment to the front of a tractor.
2. Description of the Prior Art
Vehicles including tractors and industrial equipment have available a variety of equipment that can be coupled thereto. Coupling equipment to the vehicle requires horizontal and vertical alignment of the coupler elements on the equipment and vehicle. The equipment to be coupled is often heavy, in excess of several hundred pounds, and very difficult for a lone operator to align and couple to the vehicle. In addition, the coupler itself should operate simply and preferably automatically to couple the equipment to the vehicle as the vehicle and the equipment are brought together Thus, the problem becomes one of coupling equipment to the vehicle quickly, easily and economically.
A variety of coupling mechanisms have been shown in the prior art for attaching equipment to a vehicle via a stud and a stud engaging slot. One common type has a set of jaws with a coupler plate that traps a stud in the jaw as the vehicle and equipment are brought together thereby pushing the stud into the jaws. These devices typically use a spring loaded latch plate that is acted upon by the stud and must be pivoted into a locking position by overcoming the force of the spring. When a coupling mechanism is needed to attach equipment to the front of a vehicle, it is convenient to leave the latch mechanism in a closed position when equipment is not coupled to the front of the vehicle in order to prevent the latch mechanism from grabbing debris and objects that the vehicle may encounter. This is particularly true for coupling mechanisms that are located close to the ground. Or it may be desirable to move the latch plate to a closed position to simply prevent chattering and wear of the coupling components when the vehicle is operated without the equipment attached. Pivotal resistance caused by the spring force is disasdvantageous, in that it makes it difficult for the operator to close the latch plate manually without coupling the implement and requires the exercise of care in releasing the latch plate. However some method such as the spring is needed to keep the latch plate from blocking the jaws during a coupling operation.
The spring loading of a latch plate presents a further disadvantage when a lock pin is used to hold the plate in a closed position. In such an arrangement, the spring force biasing the latch plate to an open position exerts a force on the lock pin which may make the pin difficult to remove prior to uncoupling the equipment.
To further facilitate the coupling operation, the jaws in the latch type coupler mechanism will have a V shape to forgive misalignment of the stud in one direction as the jaws receive the stud. However the jaw arrangement still requires the operator to provide fairly precise alignment between the mating coupler elements in a direction perpendicular to the plane of the jaw opening. In tongue type coupler mechanisms it is known from U.S. Pat. No. 2,120,637 to use a cone shaped opening to receive the tongue which will forgive misalignment in multiple directions. However such an arrangement adds expense, restricts access around the couplers, and is not well suited to a stud type attachment which may be secured to a pivotable arm.
Accordingly, it is an object this invention to provide a coupler that may be restrained in an open position without the drawbacks of the prior art coupling mechanisms.
More specifically, it is an object of this invention to provide a latch plate coupling mechanism that does not use a spring to restrain the latch to an open position.
It is a further object of this invention to provide a latch plate coupling mechanism that is easily moved by hand to an open or closed position.
A yet further object of this invention to provide a coupling mechanism that can be automatically activated by relative movement between the vehicle and equipment.
Another object of this invention is to provide a coupler arrangement that will forgive bi-directional misalignment during the coupling process.